1. Field
The following description relates to a wireless power transmission system, a method and an apparatus for tracking a resonance frequency in the wireless power transmission system.
2. Description of Related Art
A wireless power refers to an energy that is transferred from a wireless power transmitter to a wireless power receiver using a magnetic coupling. A wireless power transmission system includes a source device that wirelessly transmits a power, and a target device that wirelessly receives the power. The source device may be referred to as a wireless power transmitter, and the target device may be referred to as a wireless power receiver.
The source device includes a source resonator, and the target device includes a target resonator. A magnetic coupling or a resonance coupling may be formed between the source resonator and the target resonator. The source device and the target device may perform communication to transmit and receive control information and state information.
According to characteristics of a wireless environment, a distance between the source device and the target device may be changed, or matching requirements of the source resonator and the target resonator may be changed. When the distance between the source device and the target device is changed, or the matching requirements of the source resonator and the target resonator are changed, a power transmission efficiency may be changed. Accordingly, there is a need for a method of maintaining the power transmission efficiency to be constant. In order to maintain the power transmission efficiency to be constant, a resonance frequency should be accurately tracked. As such, there is a need for a method of efficiently tracking the resonance frequency in a target device using a considerable amount of power.